The Immunoassay Core (IA) provides Affiliate Investigators of the DERC with assays of peptides (insulin, proinsulin, C-peptide, Leptin, glucagon, pancreatic polypeptide) and antibodies (GAD65, ICA512, Insulin autoantibodies), performed under highly standardized conditions and with economies of scale unavailable to the individual investigator. During the past five-year funding period, the IA Core completed 18 projects for 16 Affiliate Investigators. At the present time, more than 35 projects are being supported for 34 Investigators. Work supported by the IA Core has, in this project period, resulted in over 215 publications in peer-review journals, and 19 book chapters. For the next project period, the IA Core will support at least 35 projects of 30 Affiliate Investigators. Assays are cost-effective for individual investigators; $5.00 is charged for measurements of insulin, C-peptide, $5.15 is charged for measurement of pancreatic polypeptide, glucagon, or proinsulin, GAD65 antibody and ICA512 (IA2) antibody level determinations, Leptin is charged at $6.40 and insulin autoantibody determination is charged at $7.40. In addition the Core laboratory provides insulin and glucagon radiolabeled tracer to Affiliate Investigators.